Nitroparaffin fuel



Patented Oct. 19, 1954 sTA NITROPARAFFIN FUEL poration of Illinois NoDrawing. Application June 9, 1949, Serial No. 98,157

4 Claims.

This invention relates to thermally stabilizing various nitro aliphaticmaterials used as prime mover fuels and more particularly the materialsdisclosed in copending application Serial No. 687,213 filed July 3i),1946, in the name of John A. I-Iannum, now Patent No. 2,537,526. Thisapplication is a division of application Serial No. 772,220, filedSeptember 4, 1947, in the names of John A Hannum and Joseph N. Epel.

The fuels identified in the copending application referred to above asfiled in the name of John A Hannum posses certain valuable properties asprime mover propellants, particularly for airborne devices, althoughthey may also be efficiently used for other prime movers under a varietyof circumstances as in aircraft, underwater craft, land vehicles andstationary installations. Furthermore these materials may be used as asource of power for particular types of devices such as rockets,ram-jets and the like.

Under many operating conditions it is desirable to thermally stabilizethe fuel, as by providing a catalyst toimprove its combustioncharacteristics. Heretofore certain fuel additives have been used ascatalysts to aid the fuel combustion but, unfortunately, they also actas depressants to some extent to lower the normal explosion temperaturesof the material, making it less safe to handle and more liable topremature combustion or explosion than it was before addition of thecatalyst. So far as is known, such additives have not heretofore beenused with this class of materials to raise the threshold withoutrendering them materially less useful as fuels.

A general object of the present invention is to provide an improved fuelof this kind. Another object is to provide an additive for use withfuels, particularly nitro aliphatic fuels, by which their tendency toexplode prematurely in consequence of the addition of-the catalyst isdecreased and the safety with which they may be handled im-- proved.Still another object is to provide an additive that acts as a catalystto a fuel to improve its operating characteristics as by enabling it toburn continuously rather than intermittently. Other objects of theinvention will become apparent from the specification, it beingunderstood that certain departures may be made from the followingdescription Without departing from the scope of the invention which islimited solely by the attached claims.

As indicated above, the present invention is adapted for use with thefuels that are disclosed in the copending application and that are inthe form of liquid nitro aliphatic hydrocarbons, the terms nitroaliphatic and nitroparaffin as hereinafter used being construed hereinto include both mono and polynitro derivatives. Such fuels are limitedto those that contain not more than one nitro group for each carbon atompresent. A preferred form of such fuel is nitromethane, CH3(NO2) thatitself contains much of the oxygen required during the combustion of thefuel elements in it. It is contemplated that other fuels from the classof nitro aliphatic liquids may be used in the present invention.

Examples of such fuels, in addition to nitromethane, are:

' Nitroethane CH3 .CH2.NO2 1 -nitropropane CI-B.CH2.CH2.NO22-nitropropane (CH3) 2CH.NO2 1, 1 -dinitropropane C2H5.CH (N02) 22,2-dinitropropane (CH3) 20 (N02) 2 1,2-dinitropropane CH2NO2.CHNO2.CH31 ,3-dinitropropane CH2NO2.CH2.CH2NO2 1,1 -dinitroethane CH3.CH (N02) 21,2,3-trinitropropane CH2NO2.CHNO2.CH2NO2 1,1 ,l-trinitropropane C (N02)3.CH2CH3 Such nitro aliphatics included as fuels within the scope ofthis invention include mononitromethane, dinitroethane andtrinitropropane and those nitroethanes and nitropropanes below them inoxygen content but no nitroethanes or nitropropanes that are higher inoxygen content, as for instance dinitromethane. These are all to bedistinguished from aromatic fuels such as the nitrobenzols that aredangerous to handle even by skilled persons to say nothing of personswho are not skilled in this art.

An advantage of using nitromethane or a similar partially nitratedaliphatic hydrocarbon as listed above resides in the fact that itcontains a considerable proportion of the oxygen that is required duringcombustion to burn the carbon or hydrogen in the fuel. This in turn doesnot require the presence of as much air or other oxidizing agent aswould otherwise be necessary.

55 These fuel components are non-brisant nitro aliphatic compounds,non-brisant within the terms of this disclosure meaning that the fuelmay be burned in contact with chilled iron without producing the Munroeeifect.

Although such fuels are non-brisant as defined above it frequently isdesirable to modify their explosion characteristics. When purenitromethane isxheated, it has a threshold explosion temperature of593.6 Fahrenheit. As indicated above, the addition of certain materialsserves to depress to some extent the normal explosion temperatures ofpure nitromethane. Insofar as is known no additive has been availableuntil the present invention that modifies the explosion characteristicsof nitromethane by suppressing its tendency to explode at or even belowits normal explosion temperatures and still preserves and improves thedesirable properties of nitro methane as a fuel.

The addition of a small amount, from a trace "to substantially twopercent by weight of the total fuel mixture, of a chemical compoundwhich may :be defined as including an atom of an element withpredominantly metallic properties (Metalloid), a plurality of oxygenatoms, and a poly-substituted amine radical both improves the combustionqualities of the fuels outlined above and modifies their explosioncharacteristics in the respects mentioned. A material that acts to raisethe threshold explosion temperature of the fuels listed above is thetertiary amine, pyridine salt of uranyl acetylacetonate'UO2(C5H702)aH-CeaHsN. AS an example Of the utility of the hereindescribed invention, it is pointed out that When approximately 1% byweight of the pyridine salt of uranyl acetylacetonate is added tonitromethane, there is found to be an accompanying suppression of thetendency to explode at temperatures below 615.1 Fahrenheit, an increaseof approximately 20 degrees over the threshold explosion temperature.

It is important that such salts be relatively stable in the fuels towhich they are added and do not readily break down except incident tothe process of combustion.

A fuel mixture made up in accord with the present invention will includeone or more of the fuels listed above to make up more than 98 percentbut less than 100 percent by weight of the whole. From two percent to atrace by weight will be made up of one or more stabilizers of the kinddescribed herein. These materials will act in varying degrees tostabilize the various nitro aliphatic fuels listed above, which they doby modifying their explosion characteristics; furthermore, inasmuch asthey break down incident to the process of combustion of the fuel toyield finely divided metallic oxides, they act as catalysts, causing thefuel to burn steadily and quiet- Ily, as distinguished fromintermittently, in the combustion zone.

It is intended that the patent shall cover, by suitable expression inthe appended claims, whatever features of patentable novelty reside in.the invention.

I claim:

1. A fuel mixture comprising a nitroparaiiin and from a trace to twopercent by weight of the pyridine salt of uranyl acetylacetonate.

2. A fuel mixture comprising nitromethane and the pyridine salt ofuranyl acetylacetonate, the quantity of the latter being a minorfraction of the total of the ingredients making up the mixture.

3. vA fuel mixture comprising a nitromethane and from a trace to twopercent by weight of the pyridine salt of uranyl acetylacetonate.

4. A fuel mixture comprising a liquid nitroparafiin containing not morethan one nitro group for each carbon atom present and the pyridine saltof uranyl aoetylacetonate, the quantity of the latter being a minorfraction of the total of the ingredients making up the mixture.

No references cited.

1. A FUEL MIXTURE COMPRISING A NITROPARAFFIN AND FROM A TRACE TO TWOPERCENT BY WEIGHT OF THE PYRIDINE SALT OF URANYL ACETYLACETONATE.